Rudolf Callmann (29 September 1892 – 12 March 1976[1]) was a German American legal scholar.
[2] Born in Cologne into a wealthy Jewish family, Callmann earned a doctorate in law from the University of Freiburg in 1919.
As a World War I veteran he was allowed to practice even after the Machtergreifung in 1933, but in 1936 decided to emigrate to the United States.
He was offered a research fellowship at Harvard Law School, where he worked with Zechariah Chafee, while getting accustomed to American common law, and in 1939 he passed the bar exam.
In 1949, Callmann founded the boutique law firm Greene, Callmann & Durr in New York City, along with Orville N. Greene (1908–1997) and Frank L. Durr (1904–1990), where he practiced until 1971.